Incremental repair of query plans
AssigneeMicrosoft Corporation
InventorsSurajit Chaudhuri, Ravishankar Ramamurthy
Life of this patent
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Abstract
Database systems use a plan cache to avoid the overheads (e.g., time, money) of query recompilation. Query plans can become invalidated by updates to the statistics on data or changes to the physical database design. Once a plan is invalidated, it can be repaired utilizing one or more of the disclosed embodiments. Incremental repair of query plans includes reusing parts of the current plan rather than discarding the plan entirely when it is invalidated. Repair to an existing query plan is attempted before resorting to full recompilation.
Claims20
A system that facilitates incremental repair of existing query plans, comprising:
- an optimizer component that generates a query plan and designates the generated query plan as an existing query plan;
- and
- an incremental repair component that receives the existing query plan and selectively repairs the existing query plan utilizing an incremental repair technique.
A method of selectively repairing an invalidated query plan, comprising:
- receiving a request to repair an existing query plan;
- selecting a repair technique;
- and
- applying the repair technique to the existing query plan.
A computer executable system that provides repair of query plans, comprising:
- means for receiving a request for a database information;
- means for retrieving a query plan that includes the database information;
- means for determining that the retrieved query plan is invalid;
- means for repairing the retrieved query plan;
- and
- means for presenting a result of the repaired query plan in response to the received request.
Dependencies are inferred from the claim text.